Song learning in birds is a good animal model to study brain processes involved in speech acquisition. Birdsong and speech are both learned to auditory information. Both require that a correct model be recognized and imitated. In both cases encoding and decoding may be closely associated. It seems likely that the highest forebrain nucleus for vocal control in songbrids, the hyperstriatum ventrale, pars caudale (HVc), is involved in song learning. We speculate that HVc in canaries may have a role comparable to that of Broca's area in the human brain, contribution both to the perception and production of conspecfic vocalizations. To test this possibility we will see how partial or total lesions of HVc affect selective responsiveness to conspecific song. Other experiments using single unit recording techniques and intracellular HRP injections will identify HVc units that respond to various sounds, including natural and synthetic song, then determine how their physiological and anatomical profiles vary, as a function of age, sex, season, hormonal treatment and side of brain. We will want to know what is the connectivity of such units. For example, do they project to the next lower efferent nucleus involved in song control, the nucleus robustus of the archistriatim? Out of this work we hope to glean facts that will: 1) better describe anatomical and physiological relations between encoding and decoding networks; 2) lead to an understanding of hemispheric lateralization of function; and 3) shed light on the mechanisms and significance of the newly discovered anatomical seasonality of brain pathways involved in learning. We can make a canary aphasic for song. We are beginning to understand the variables effecting its recovery of this function. This information may become usefull for improving the prognosis of human patients in which brain lesion has led to an impairment of speech, language and other cognitive skills.